Android support

basic android support including rendering, bullet physics, png support and loading files directly from the zipped apps folder.
audio does not yet work
Merge branch 'refs/heads/master' into android

Conflicts:
	Engine/Graphics/sgObjectFiles.cpp
Fixed android wrapper to work for the android app lifecycle, support for ouya gamepad, basic ouya support and updated physics example.
added the crytec sponza scene, another animated test model and a anything to png converter, which however uses my system paths...
Updated the sgAnimation sample which should now just work on iOS.